In many f1uid circuits, such as the hydraulic circuit in an agricultural tractor, provision is made to add and remove remote functions such as a hydraulic cylinder on an implement attached to the tractor to the main hydraulic system. This provision for adding or subtracting is usually in the form of a female coupler which will receive a male coupler on the end of a hydraulic line leading to the remote function. Examples of such female couplers are shown in co-pending U.S. application Ser. No. 696,542 filed on Jan. 30, 1985 by Kugler et al as a continuation of Ser. No. 438,120 filed on 1 Nov. 1982 and U.S. Ser. No. 491,519 filed on 4 May 1983 by Kugler. Both of the co-pending applications referred to disclose a female coupler which provides for easy coupling to a male coupler which may be under pressure due to either thermal expansion or a load on the remote function to which the male coupler is attached, has provision to utilize fluid pressure to forceably open the check valve of the male coupler which may be under pressure, and incorporates a flow check valve which will prevent the check valve of the male coupler from closing should the coupled male and female couplers be subjected to alternate surges of vacuum and pressure.
The female coupler disclosed in the aforementioned co-pending U.S. application Ser. No. 696,542 was an improvement over previous couplers in that it incorporated the flow check valve for preventing unwanted closure of the check valve in the male coupler, and the coupler disclosed in the aforementioned co-pending U.S. application Ser. No. 491,519 was an improvement over the other in that it incorporated a much simplified and inexpensive flow check valve. However, the couplers disclosed in both of the aforementioned co-pending U.S. applications required many parts to perform all the functions and were thus expensive to manufacture, were difficult to assemble and disassemble thus making repair so expensive that they were considered nonrepairable and, due to the large number of parts which could result in tolerance buildup, were subject to valve binding.